Cellulose esters are used extensively in lacquer coatings because they are compatible with many resins and additives, they exhibit good gap-filling properties, they dry quickly and can be sanded or rubbed soon after application, they exhibit low toxicity, and they form a very aesthetically-pleasing coating on a variety of substrates. Such coatings are "forgiving" and are said to be "user friendly" because they can be applied reproducibly and can be repaired or even removed with the use of solvent. Such lack of solvent resistance is an advantage for lacquer handling since equipment used to apply the lacquer can be readily cleaned, but solvent resistance of the applied coating is highly desirable, particularly if the coating is intended to be protective in nature. Moreover, cellulose ester lacquer coatings tend to be rather soft and are easily scratched.
Thus there is a need for a suitably modified cellulose ester still having thermoplastic and aesthetic properties of the original cellulose ester and after application as a coating can be transformed into a three-dimensional polymeric network with significantly improved resistance to solvents and scratching.
The prior art discloses certain compositions containing admixtures of certain cellulose esters and certain melamine compounds (see U.S. Pat. Nos. 4,007,144; 4,133,783 and 4,251,404); however, heretofore substantially non-crosslinked modified cellulose esters as described hereinbelow have been unknown.